Question

import java.util.Scanner;
public class Perimeter {


public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    System.out.println("Please enter X1: ");
    double X1 = scan.nextDouble();
    System.out.println("Please enter Y1: ");
    double Y1 = scan.nextDouble();
    System.out.println("Please enter X2: ");
    double X2 = scan.nextDouble();
    System.out.println("Please enter Y2: ");
    double Y2 = scan.nextDouble();
    System.out.println("Please enter X3: ");
    double X3 = scan.nextDouble();
    System.out.println("Please enter Y3: ");
    double Y3 = scan.nextDouble();

    finddistance(X1,Y1,X2,Y2,X3,Y3);
    double answer = triperimeter(base1, base2, base3);
    System.out.println(answer);

}

public static finddistance(double X1, double Y1, double X2, double Y2, double X3, double Y3){
    double base1 = Math.sqrt(Math.pow((X2 - X1),2) + Math.pow((Y2 - Y1),2));
    double base2 = Math.sqrt(Math.pow((X3 - X1),2) + Math.pow((Y3 - Y1),2));
    double base3 = Math.sqrt(Math.pow((X3 - X2),2) + Math.pow((Y3 - Y2),2));
}

public static double triperimeter(double base1, double base2, double base3){
    return (double) base1 + base2 + base3;
}
}

我们正在学习如何立即使用多种方法编写代码，我认为我的错误如下：

在方法finddistance中，我需要以某种方式与代码中的所有方法共享/返回变量base123，但是我不知道该怎么做。

当我编译这段代码时，它只会给我一个错误消息：无效的方法声明，需要返回类型。在公共静态finddistance线上。

Answer 1

我怀疑您的老师想要的是拥有一种findDistance方法，该方法只能计算一个距离，但是您会调用三次。然后，当您确定了这三种长度时，可以根据需要将它们全部添加到单独的方法中。

还请注意，通常使用Math.hypot代替Math.sqrt和Math.pow更准确。

public static void main(String[] args) {
    Scanner scan = new Scanner(System.in);
    System.out.println("Please enter Ax: ");
    double ax = scan.nextDouble();
    System.out.println("Please enter Ay: ");
    double ay = scan.nextDouble();
    System.out.println("Please enter Bx: ");
    double bx = scan.nextDouble();
    System.out.println("Please enter By: ");
    double by = scan.nextDouble();
    System.out.println("Please enter Cx: ");
    double cx = scan.nextDouble();
    System.out.println("Please enter Cy: ");
    double cy = scan.nextDouble();

    double lengthA = findDistance(bx, by, cx, cy);
    double lengthB = findDistance(ax, ay, cx, cy);
    double lengthC = findDistance(ax, ay, bx, by);

    double answer = perimeter(lengthA, lengthB, lengthC);
    System.out.println(answer);

}

public static double findDistance(double x1, double y1, double x2, double y2){
    return Math.hypot( x2 - x1, y2 - y1 ); 
}

public static double perimeter(double length1, double length2, double length3) {
    return length1 + length2 + length3;
}

Answer 2

该错误非常明确地表明“需要返回类型”。您缺少方法finddistance的返回类型。您可能需要修改代码：

以double数组形式返回计算出的“基数”
将每个碱基传递给triperimeter方法

类似这样的东西：

 import java.util.Scanner;

    public class Perimeter
    {

        public static void main(String[] args)
        {
            Scanner scan = new Scanner(System.in);
            System.out.println("Please enter X1: ");
            double X1 = scan.nextDouble();
            System.out.println("Please enter Y1: ");
            double Y1 = scan.nextDouble();
            System.out.println("Please enter X2: ");
            double X2 = scan.nextDouble();
            System.out.println("Please enter Y2: ");
            double Y2 = scan.nextDouble();
            System.out.println("Please enter X3: ");
            double X3 = scan.nextDouble();
            System.out.println("Please enter Y3: ");
            double Y3 = scan.nextDouble();

            double bases[] = finddistance(X1, Y1, X2, Y2, X3, Y3);
            double answer = triperimeter(bases[0], bases[1], bases[2]);
            System.out.println(answer);

        }

        public static double[] finddistance(double X1, double Y1, double X2, double Y2, double X3, double Y3)
        {
            double base1 = Math.sqrt(Math.pow((X2 - X1), 2) + Math.pow((Y2 - Y1), 2));
            double base2 = Math.sqrt(Math.pow((X3 - X1), 2) + Math.pow((Y3 - Y1), 2));
            double base3 = Math.sqrt(Math.pow((X3 - X2), 2) + Math.pow((Y3 - Y2), 2));

            return new double[] { base1, base2, base3 };
        }

        public static double triperimeter(double base1, double base2, double base3)
        {
            return (double) base1 + base2 + base3;
        }
    }

您还可以选择设置base1，base2和base3全局静态变量。

Answer 3

尝试返回双打数组

public static double [] finddistance(double X1, double Y1, double X2, double Y2, double X3, double Y3){
    double [] rv = new double [3];
    rv [0] = Math.sqrt(Math.pow((X2 - X1),2) + Math.pow((Y2 - Y1),2));
    rv [1] = Math.sqrt(Math.pow((X3 - X1),2) + Math.pow((Y3 - Y1),2));
    rv [2] = Math.sqrt(Math.pow((X3 - X2),2) + Math.pow((Y3 - Y2),2));
    return rv;
}

修改

然后将您的呼叫更改为

double[] rv = finddistance(X1,Y1,X2,Y2,X3,Y3);

然后

double answer = triperimeter(rv[0], rv[1], rv[2]);

Answer 4

这些行

double base1 = Math.sqrt(Math.pow((X2 - X1),2) + Math.pow((Y2 - Y1),2)); double base2 = Math.sqrt(Math.pow((X3 - X1),2) + Math.pow((Y3 - Y1),2)); double base3 = Math.sqrt(Math.pow((X3 - X2),2) + Math.pow((Y3 - Y2),2));

看起来很相似，你不觉得吗？不要尝试同时计算所有三个函数，而应尝试重用该函数，因为您可能希望以后再使用它，但只能在一个基础上使用它。

Answer 5

声明静态变量

double base1=0; double base2=0; double double base3=0;

main（）之上并在finddistance（）中分配值；
将返回类型设为'void'到finddistance（）

Answer 6

double answer = triperimeter(base1, base2, base3);

1）参数未定义，base1，base2是什么？尝试定义

2）public static finddistance(double X1, double Y1, double X2, double Y2, double X3, double Y3)

方法声明不正确，方法应至少具有返回类型。

3）遵循方法类的命名约定标准

通过使用多种方法，找到具有给定坐标的三角形的周长

6 个答案: